CN114506925A

CN114506925A - Method for removing DEHP in landfill leachate

Info

Publication number: CN114506925A
Application number: CN202210093745.1A
Authority: CN
Inventors: 方程冉; 仇立波; 李红; 刘宏远
Original assignee: Zhejiang University of Technology ZJUT
Current assignee: Zhejiang University of Technology ZJUT
Priority date: 2022-01-26
Filing date: 2022-01-26
Publication date: 2022-05-17

Abstract

The invention discloses a method for removing DEHP in landfill leachate. The invention adopts the A/A/O process to treat the landfill leachate, the hydraulic retention time ratio of the landfill leachate in the anaerobic tank, the anoxic tank and the aerobic tank is 1:1:4, and the optimal hydraulic parameters of the A/A/O process are set; preparing bacillus, pseudomonas and mycobacterium into microorganism suspension, adding the microorganism suspension into sludge in an aerobic tank, uniformly stirring, operating an A/A/O (anaerobic/anoxic/oxic) process according to optimal hydraulic parameters, and removing DEHP in the landfill leachate; and then preparing the microorganism suspension into immobilized microorganisms, adding the immobilized microorganisms into an aerobic tank, operating an A/A/O (anaerobic/anoxic/oxic) process according to optimal hydraulic parameters, and finally removing DEHP in the landfill leachate. According to the invention, under the condition of the optimal hydraulic parameters of the A/A/O process, the microorganism suspension and the immobilized microorganism are inoculated in sequence, so that the DEHP removal rate is obviously improved.

Description

Method for removing DEHP in landfill leachate

Technical Field

The invention relates to the technical field of landfill leachate pollutant removal, in particular to a method for removing di (2-ethylhexyl) phthalate (DEHP) in landfill leachate.

Background

The landfill leachate is a secondary pollutant of a life cycle of a domestic garbage landfill and has the characteristics of complex pollutant composition, high pollutant concentration and poor biodegradability. Landfill leachate contains various organic pollutants, such as Phthalic Acid Esters (PAEs) and the like. PAEs are widely used as additives for plastics, paints, cosmetics, etc., and these are generally disposed of and landfilled with household garbage. As PAEs are only connected with parent bodies such as plastics by Van der Waals force, PAEs are easy to dissolve out and enter landfill leachate. PAEs are suspected mutagens and carcinogens, and are listed as priority pollutants and endocrine disruptors by the U.S. environmental protection agency, the european union, and the national center for environmental monitoring.

Therefore, it is desirable to understand how to effectively remove PAEs from landfill leachate, thereby minimizing the potential for their release into the environment. Currently, methods for treating PAEs mainly include physical, chemical and biological methods. In air, photolysis is an important degradation pathway for PAEs. In water, the half-life of PAEs is long and the degree of complete mineralization is low. Photochemical oxidation and photocatalytic oxidation are introduced to promote degradation of these species due to photolytic limitations. Biodegradation is a major pathway affecting the behavior and homing of PAEs in the environment. PAEs are available to a variety of bacteria and actinomycetes in both aerobic and anaerobic environments, with degradation rates related to the length of the molecular alkyl chain. Furthermore, biodegradation is considered to be the optimal method for treating refractory organics due to its low cost and low investment.

Di (2-ethylhexyl) phthalate (DEHP) is the most common PAEs in organisms, river water, sea water, ground water, sediments and soil. High concentrations of DEHP are also present in landfill leachate. Research shows that the DEHP has a long molecular chain and a complex structure, and has lower biodegradability than other PAEs (such as dibutyl phthalate (DBP)).

The anaerobic/anoxic/aerobic (A/A/O) process is an alternative operation of anaerobic, anoxic and aerobic, and can simultaneously remove organic carbon, nitrogen and phosphorus pollutants in wastewater. Moreover, the operation process makes the filamentous fungi difficult to grow and reproduce, and avoids the sludge bulking problem frequently occurring in the traditional activated sludge method. Compared with the advanced treatment after the secondary treatment by the common activated sludge method, the method has the advantages of low investment and low operation cost, does not have a large amount of excess sludge and has good environmental benefit. Research shows that when leachate is treated by the conventional A/A/O process, the removal efficiency of DEHP is about 75-78%, which inevitably results in that residual DEHP cannot be removed and is discharged to the external environment.

Different operating conditions of the wastewater treatment process can affect the performance of the activated sludge, and thus the removal efficiency of pollutants in the wastewater. Settings such as Hydraulic Retention Time (HRT) of the bioreactor in the a/O process, sludge retention time, out-sludge reflux ratio, in-sludge reflux ratio, dissolved oxygen concentration, etc., will all have an impact on the efficiency of contaminant removal. In addition, bioaugmentation is often used as an effective means to enhance contaminant removal in wastewater biological treatment systems. The biological strengthening technology is to add dominant degrading bacteria which are difficult to degrade organic pollutants into a biological treatment system, improve the concentration of effective microorganisms, and increase the degradation rate of the pollutants, thereby improving the removal efficiency of the original biological treatment process on target pollutants.

However, the hydraulic conditions of the a/O process that affect the efficiency of DEHP removal in leachate are not clear, and it is clear whether the isolated DEHP dominant bacteria can adapt to the complex matrix environment.

Disclosure of Invention

Aiming at the problems of difficult degradation and low degradation rate of DEHP in the current landfill leachate, the invention provides a method for removing di (2-ethylhexyl) phthalate (DEHP) in the landfill leachate, which improves the removal rate of DEHP in the leachate by optimizing hydraulic parameters of an A/A/O process and further improving the original biological treatment process through a biological enhancement technology, realizes the harmless treatment of the difficult degradation organic pollutants such as environmental hormones and the like in the leachate, and solves the problems of difficult removal and low removal rate of DEHP in the current landfill leachate.

The technical scheme adopted by the invention is as follows:

the method of the invention comprises the following steps:

1) setting of optimal hydraulic parameters for A/A/O process

Treating the landfill leachate by adopting an A/A/O process, and setting the optimal hydraulic parameters of the A/A/O process;

2) preparation and addition of microbial suspension

Respectively carrying out amplification culture on bacillus, pseudomonas and mycobacterium to respectively obtain corresponding bacteria liquid after amplification culture, inoculating the three bacteria liquid after amplification culture into a potato glucose broth culture medium according to the ratio of 2:1:1, mixing and culturing for 3d, centrifuging at the rotating speed of 8000rpm for 10min, taking precipitate, suspending in distilled water to prepare a microorganism suspension, adding the microorganism suspension into sludge in an aerobic tank of an A/A/O process, uniformly stirring, operating the A/A/O process according to optimal hydraulic parameters, and removing DEHP in the garbage percolate.

The method further comprises the following steps:

3) preparation and addition of immobilized microorganisms

Preparing a mixed solution of 4% by mass of sodium alginate, 4% by mass of polyvinyl alcohol and 1% by mass of activated carbon with distilled water, taking the mixed solution as an immobilized embedding agent, mixing the immobilized embedding agent with the microorganism suspension obtained in the step 2) according to the volume ratio of 1:1 to obtain a mixed microorganism embedding agent, absorbing the mixed microorganism embedding agent, adding the mixed microorganism embedding agent into 5% by mass of calcium chloride, crosslinking for 5 hours to prepare immobilized microorganisms, adding the immobilized microorganisms into an aerobic tank of an A/A/O process, wherein the adding amount of the immobilized microorganisms is 15% of the effective volume of the aerobic tank, operating the A/A/O process according to optimal hydraulic parameters, and removing DEHP in the landfill leachate.

The landfill leachate is old landfill leachate.

In the step 1), the concentration of dissolved oxygen in the anaerobic tank is 0.1-0.2 mg/L, the concentration of dissolved oxygen in the anoxic tank is 0.1-0.6 mg/L, and the concentration of dissolved oxygen in the aerobic tank is 6-7.5 mg/L.

The hydraulic retention time ratio of the landfill leachate in the anaerobic tank, the anoxic tank and the aerobic tank is 1:1:4,

the optimal hydraulic parameters of the A/A/O process are as follows: the hydraulic retention time is 3 days, the internal reflux ratio of the sludge is 200 percent and the external reflux ratio of the sludge is 60 percent.

In the step 2), the mixed culture conditions are that the temperature is 28-30 ℃, the rotating speed is 140-160 rpm, and the shaking culture is carried out.

In the step 2), the adding amount of the microorganism suspension is 10% of the volume of the sludge in the aerobic tank.

The mass ratio of bacillus, pseudomonas and mycobacterium in the microbial suspension in the step 2) is 2:1: 1.

The invention has the beneficial effects that:

1. according to the invention, through optimizing hydraulic parameters of the A/A/O process, the removal rate of DEHP is obviously improved from 58.0-78.5% and stabilized at 76.5-81.2%, and the practicability is strong.

2. Under the condition of the optimal hydraulic parameters of the A/A/O process, DEHP degradation dominant bacteria are further inoculated, the microbial suspension and immobilized microorganisms are sequentially inoculated, the DEHP removal rate is further improved, and is increased from 76.5% -81.2% before inoculation to 82.6% -85.3% until the DEHP removal rate is further stabilized at 88.8% -91.7%, the method is a removal effect which cannot be achieved by many existing technologies at present, and an effective technical method is provided for degrading DEHP in landfill leachate.

Drawings

FIG. 1 is a graph of DEHP removal for different hydraulic parameters from example 1; wherein, in a of fig. 1: HRT 6d, II: HRT 4.5d, III: HRT 3d, IV: HRT 2 d; i in b of fig. 1: internal reflux ratio 100%, II: internal reflux ratio 180%, III: the internal reflux ratio is 200 percent; IV: the internal reflux ratio is 300 percent; i in c of fig. 1: external reflux ratio 60%, II: external reflux ratio 80%, III: the external reflux ratio is 100 percent.

FIG. 2 is a graph of the significance of the DEHP removal differences under different hydraulic parameters in example 1; wherein A, B and C refer to the significance of the difference of the average DEHP removal rate of the same hydraulic parameter of the reactor under different values (p < 0.05).

FIG. 3 is a graph of DEHP removal rate before and after inoculation of the dominant bacteria suspension in example 2; wherein, I: before inoculation of the suspension; II: after inoculation of the suspension.

FIG. 4 is a graph showing the DEHP removal rate before and after inoculation of the immobilized microorganism in example 3; wherein, I: before inoculation of immobilized microorganisms; II: after inoculation of the immobilized microorganism.

FIG. 5 is a graph of the optimization steps versus DEHP removal in examples 1-3.

Detailed Description

The invention is described in further detail below with reference to the figures and the embodiments.

It should be understood that these examples are for illustrative purposes only and are not intended to limit the scope of the present invention. The following examples are conducted under conditions not specified, usually according to conventional conditions, or according to conditions recommended by the manufacturer.

In the embodiment of the invention, the DEHP in the landfill leachate is measured by adopting a solid phase extraction-high performance liquid chromatography method. A sunfire-C18 column was used, the column temperature being 25 ℃. The mobile phase was a mixture of methanol and water (90:10v: v) at a flow rate of 1.0 mL/min. The UV detector wavelength was 225nm, under which the limit of quantitation of DEHP was determined. The whole analysis process is monitored by control samples such as method blank, labeling blank, matrix labeling parallel sample, sample parallel sample, and the like, and the influence of the preparation of the sample and the matrix is monitored by the recovery rate indicator. And correcting the quantitative result of DEHP in the landfill leachate through the recovery rate. In specific implementation, the limit of the quantification of DEHP is 0.2 mu g/L; the recovery rate of DEHP in the percolate is 85.5-90.1%.

The experimental object in the embodiment is old landfill leachate of a certain sealing landfill in Zhejiang province, and the old landfill leachate is leachate of garbage with the landfill time longer than 10 years.

Example 1

Setting of optimal hydraulic parameters for A/A/O process

A: DEHP removal rate under different hydraulic retention time conditions

The A/A/O reactor consists of a 6-L anaerobic tank (A1), a 6-L anoxic tank (A2), a 24-L aerobic tank (O) and a 25-L sedimentation tank, which are all made of organic glass. And the sludge returns to the anaerobic tank from the bottom of the sedimentation tank through a peristaltic pump. The mixed liquid is circulated from the aerobic tank to the anoxic tank by a peristaltic pump. The Mixed Liquor Suspended Solids (MLSS) in the A/A/O reactor was 3000 mg/L. The whole A/A/O reactor was placed in a thermostatic chamber at 25 ℃. The hydraulic retention time ratio of the anaerobic tank, the anoxic tank and the aerobic tank is 1:1: 4. The dissolved oxygen concentration in the anaerobic tank, the anoxic tank and the aerobic tank is respectively controlled to be 0.1-0.2 mg/L, 0.2-0.6 mg/L and 6-7.5 mg/L.

In the specific implementation, a certain amount of DEHP standard solution is added into the aged landfill leachate, and the initial DEHP concentration of the water inlet of the A/A/O reactor is measured to be 5151-5204 mu g/L. In the case of an internal reflux ratio of 200%, an external reflux ratio of 100% and a total hydraulic retention time of 6d, 4.5d, 3d and 2d, stages I, II, III and IV were provided, respectively (a in FIG. 1). Two cycles were run for each hydraulic retention time. Samples were taken from each reaction cell periodically and the DEHP concentration was determined. The DEHP measurement adopts solid phase extraction-high performance liquid chromatography. A sunfire-C18 column was used, the column temperature being 25 ℃. The mobile phase was a mixture of methanol and water (90:10v: v) at a flow rate of 1.0 mL/min. The UV detector wavelength was 225nm, under which conditions a limit of quantitation for DEHP of 0.2. mu.g/L was determined. The whole analysis process is monitored by control samples such as method blank, labeling blank, matrix labeling parallel sample, sample parallel sample, and the like, and the influence of the preparation of the sample and the matrix is monitored by the recovery rate indicator. The quantitative result of DEHP in the landfill leachate is corrected through the recovery rate of DEHP (85.5% -90.1%). The DEHP concentration in the water inlet and outlet of the reactor is measured, the removal rate of the DEHP is calculated, and the removal rate of the DEHP under different hydraulic retention time conditions is compared to obtain the optimal hydraulic retention time.

As a result, as shown in a of figure 1, the DEHP concentration in the leachate outlet water is obviously lower than that in the inlet water, and the A/A/O treatment process has higher DEHP removal rate. The removal rate of DEHP in the whole process is 58.0-83.5%. When the hydraulic retention time is respectively 6, 4.5, 3 and 2d, the removal rate of DEHP is respectively 58.0-78.5%, 74.8-79.3%, 77.7-80.5% and 75.8-79.9%. Further, at hydraulic retention times of 6, 4.5, 3 and 2d, the average removal rates of DEHP were 77.1%, 77.2%, 78.8% and 77.7%, respectively, as shown in a of fig. 2. It can be seen that when the hydraulic retention time is 3d, the removal rate of DEHP is significantly higher than other hydraulic retention times. Furthermore, at a hydraulic retention time of 3d, a maximum efficiency of 80.5% removal of DEHP also occurred at this time.

It can be seen that 3d is the optimal hydraulic retention time for the a/O reactor to remove DEHP from old landfill leachate, with an average DEHP removal of 78.8%.

B: DEHP removal rate under different sludge internal reflux ratio conditions

Under the condition that the optimal hydraulic retention time of the reactor is 3d, and the sludge external reflux ratio is 100%, the sludge internal reflux ratio is respectively set to be 100%, 180%, 200% and 300%. The DEHP concentration in the water inlet and outlet of the reactor is measured, the removal rate is calculated, and the optimal sludge internal reflux ratio is obtained and respectively corresponds to stages I, II, III and IV of different lattices in the b of the figure 1.

As can be seen from b of fig. 1, when the sludge reflux ratio was increased from 100% to 200%, the average removal rate of DEHP was increased from 68.9% to 78.5%. When the internal reflux ratio was 300%, the average removal rate of DEHP was 75.6%. As shown in b of fig. 2, when the internal reflux ratio is 200%, the average removal rate of DEHP is significantly higher than that of the other conditions.

It can be seen that 200% is the optimum internal reflux ratio for the A/A/O reactor to remove DEHP from the aged landfill leachate, and the average removal rate of DEHP is 78.5%.

C: DEHP removal rate under different sludge external reflux ratio conditions

Under the conditions of the optimal hydraulic retention time 3d and the sludge internal reflux ratio of 200%, the sludge external reflux ratio of the reactor is set to be 60%, 80% and 100%. Measuring DEHP concentrations in the inlet water and the outlet water of the reactor and calculating the removal rate of the DEHP concentrations to obtain the optimal sludge external reflux ratio which respectively corresponds to stages I, II and III of different grids of c in the figure 1.

As shown in c of fig. 1 and c of fig. 2, when the sludge external reflux ratio of the reactor was 60%, 80% and 100%, respectively, the average removal rate of DEHP was 79.0%, 78.7% and 78.2%, respectively. There were no significant differences between the data. It can be seen that the external sludge recirculation ratio of the a/O reactor has no significant effect on the removal of DEHP from old landfill leachate. However, the analysis of the conventional index of water quality shows that the removal rate of the pollutants is the highest and most stable when the external reflux ratio is 60%.

Thus, considering the overall efficiency of the a/O reactor, 60% is considered the optimal external reflux ratio for the a/O reactor to remove DEHP from old landfill leachate, with an average DEHP removal of 79.0%.

It follows that the optimum hydraulic parameters for the A/A/O process are set as: the hydraulic retention time is 3 days, the internal reflux ratio of the sludge is 200 percent and the external reflux ratio of the sludge is 60 percent.

Example 2

Preparation and dosing of the microbial suspension at the optimal hydraulic parameters of the A/A/O Process set forth in example 1

Separation, culture and identification of A degradation dominant bacteria

Separation: the separation source is sludge in a sedimentation tank of a leachate treatment system of a certain refuse landfill, and the inorganic salt culture medium (g/L) specifically comprises the following components: k is₂HPO₄·3H₂O 0.4；(NH₄)₂HPO₄ 0.5；MgSO₄·7H₂O 0.05；CaCl₂ 0.1；FeCl₃·6H₂O0.01; agar 18.0; pH 7.4. Sterilizing at 121 deg.C for 30 min. 1g of sludge is taken and dissolved into 40mL of sterile water, and the mixture is evenly shaken. 1mL of the above solution was plated on 15mL of an inorganic salt plate medium by the plate plating method. The inorganic salt medium used DEHP as the sole carbon and energy source (100- & lt 500- & gt mg/L). And after culturing in a dark environment at 30 ℃ for 7d, picking out completely developed bacterial colonies, inoculating the bacterial colonies to the same inorganic salt culture medium, carrying out plate streaking separation, and repeating streaking separation according to the morphology of the bacterial colonies and the observation result of a microscope until pure bacterial strains are obtained.

DEHP degradation capacity determination: inoculating 2% of the strain into 50mL of inorganic salt medium containing 500mg/L DEHP, shake culturing at 30 deg.C for 3d, taking out, centrifuging, collecting supernatant, extracting with 10mL of n-hexane for three times, combining organic phases, and adding anhydrous Na₂SO₄Drying, concentrating to 1mL, drying with nitrogen gas, dissolving with methanol of the same volume, and measuring DEHP concentration by HPLC, and repeating three times for each treatment without adding bacteria solution. The strain with the same condition and fast degradation rate is determined as DEHP degradation dominant bacteria.

And (3) identification: the morphological analysis adopts a perspective electron microscope (H-600), and the physiological and biochemical experiment refers to Dongxiu bead and the like (2001); 16S rDNA amplification and sequencing: the cells were collected by centrifugation, genomic DNA was extracted using a DNA extraction kit, and 16S rDNA amplification was performed on a PCR apparatus using the extracted genomic DNA as an amplification template. Purifying and sequencing a PCR product to obtain a strain 16SrDNA sequence, performing homology analysis on a sequencing result in databases such as Genbank and the like, and determining that DEHP degrading dominant bacteria comprise bacillus, pseudomonas and mycobacterium.

Preparation and addition of B degradation dominant bacteria suspension

Selecting the bacillus, the pseudomonas and the mycobacterium as specifically added microorganisms, inoculating the bacteria liquid obtained after the amplification culture of the microorganisms into a potato glucose broth culture medium according to the ratio of 2:1:1, performing mixed oscillation culture for 3d under the conditions that the temperature is 28-30 ℃, the rotating speed is 140-160 rpm, performing oscillation culture, centrifuging at the rotating speed of 8000rpm for 10min, taking the precipitate, and suspending the precipitate in distilled water to prepare a microorganism suspension, wherein the mass ratio of the bacillus, the pseudomonas and the mycobacterium in the microorganism suspension is 2:1: 1. And (4) shutting down the reactor, after the sludge in the aerobic tank is settled, extracting supernatant as much as possible, and placing the obtained sludge in the aerobic tank in a sealed glass bottle. And adding the microbial suspension into the sludge in the aerobic tank and uniformly stirring, wherein the adding amount of the microbial suspension is 10% of the volume of the sludge in the aerobic tank. Opening an A/A/O reactor water inlet and outlet valve and an internal and external reflux pump, operating the A/A/O reactor according to the optimal hydraulic parameters, namely, the optimal hydraulic retention time is 3d, and the optimal sludge internal and external reflux ratio is respectively 200% and 60%, ensuring that the A/A/O reactor stably operates under the conditions, keeping the sampling point positions consistent in two operation periods, periodically measuring the DEHP concentration in the water inlet and outlet of the A/A/O reactor and calculating the removal rate of the DEHP concentration, and analyzing the influence of the inoculation of the DEHP degradation dominant bacteria suspension on the removal of the DEHP.

The result is shown in figure 3 (I and II correspond to the suspension inoculation front and back respectively), and the removal rate of DEHP is 76.5% -81.2% before the suspension of DEHP degrading dominant bacteria is inoculated; after inoculation, the removal rate of DEHP is stabilized at 82.6% -85.3%. Before inoculation, the average concentration of DEHP in inlet water of the reactor is 5177.5 mu g/L, the average concentration of DEHP in outlet water of the reactor is 1084.6 mu g/L, and the average removal rate is 79.0 percent; after inoculation, the average concentration of DEHP in the reactor feed water was 5185.1 μ g/L, the average concentration of DEHP in the effluent was 845.1 μ g/L, and the average removal rate was 83.7%.

It can be seen that under the condition of the optimal hydraulic parameters of the A/A/O reactor, after the suspension of the DEHP degrading dominant bacteria is inoculated, the average removal rate of the DEHP by the A/A/O reactor is 83.7%, which is obviously higher than that of the DEHP before inoculation.

Example 3

Preparation and addition of immobilized microorganisms on the basis of example 2

Preparing a mixed solution of 4% by mass of sodium alginate, 4% by mass of polyvinyl alcohol and 1% by mass of activated carbon by using distilled water, wherein the activated carbon is used for increasing the permeability of immobilized particles, taking the mixed solution as an immobilized embedding agent, mixing the immobilized embedding agent and the microorganism suspension prepared in the example 2 according to the volume ratio of 1:1 to obtain a mixed microorganism embedding agent, absorbing the mixed microorganism embedding agent, adding the mixed microorganism embedding agent into 5% by mass of calcium chloride, and crosslinking for 5 hours to prepare the immobilized microorganism with the diameter of about 4 mm. The prepared immobilized microorganism is added into the aerobic tank of the A/A/O reactor in stable operation in example 2, and the adding amount of the immobilized microorganism is 15% of the effective volume of the aerobic tank. In two operation periods, keeping the sampling point positions consistent, periodically measuring the DEHP concentration in the water inlet and the water outlet of the reactor, calculating the removal rate of the DEHP, and analyzing the influence of immobilized microorganism inoculation on the removal of the DEHP.

As shown in fig. 4 (i and ii correspond to before and after inoculation of immobilized microorganisms, respectively), the removal rate of DEHP is 82.6% -85.3% before inoculation of immobilized microorganisms of DEHP degrading dominant bacteria; after inoculation, the removal rate of DEHP is stabilized at 88.8% -91.7%. Before inoculation, the average removal rate of DEHP is 83.7%; after inoculation, the average removal was 90.3%.

In conclusion, under the conditions of the optimal hydraulic parameters of the reactor and the optimization of the DEHP degradation dominant bacteria suspension, after the immobilized microorganisms are inoculated, the average removal rate of the DEHP by the A/A/O reactor is remarkably improved to 90.3%, the degradation rate is stable, and the influence of the change of the water inlet concentration is small.

According to the invention, the operation hydraulic parameters of the A/A/O reactor are optimized by regulating and controlling the hydraulic retention time, the internal reflux ratio of sludge and the external reflux ratio of sludge, and then DEHP degradation dominant bacteria suspension (namely microorganism suspension) and immobilized microorganisms are inoculated in sequence, so that the DEHP removal rate in the aged landfill leachate is stabilized at 88.8-91.7%, and the DEHP removal rate in each optimization step is shown in figure 5.

The foregoing is merely an example of the present invention and common general knowledge in the art of specific structures and/or features of the invention has not been set forth herein in any way. It should be noted that, for those skilled in the art, without departing from the structure of the present invention, several changes and modifications can be made, which should also be regarded as the protection scope of the present invention, and these will not affect the effect of the implementation of the present invention and the practicability of the patent.

Claims

1. A method for removing DEHP in landfill leachate is characterized by comprising the following steps:

1) setting of optimal hydraulic parameters for A/A/O process

2) preparation and addition of microbial suspension

2. The method for removing DEHP in landfill leachate according to claim 1, wherein the method further comprises the steps of:

3) preparation and addition of immobilized microorganisms

3. The method as claimed in claim 1 or 2, wherein the landfill leachate is aged landfill leachate.

4. The method for removing DEHP in landfill leachate according to claim 1, wherein in step 1), the concentration of dissolved oxygen in the anaerobic tank is 0.1-0.2 mg/L, the concentration of dissolved oxygen in the anoxic tank is 0.1-0.6 mg/L, and the concentration of dissolved oxygen in the aerobic tank is 6-7.5 mg/L.

5. The method for removing DEHP in landfill leachate according to claim 1, wherein the hydraulic retention time ratio of the landfill leachate in the anaerobic tank, the anoxic tank and the aerobic tank is 1:1: 4.

6. The method for removing DEHP in landfill leachate according to claim 1, wherein the optimal hydraulic parameters of the a/O process are specifically: the hydraulic retention time is 3 days, the internal reflux ratio of the sludge is 200 percent and the external reflux ratio of the sludge is 60 percent.

7. The method for removing DEHP in landfill leachate according to claim 1, wherein in the step 2), the mixed culture conditions are that the temperature is 28-30 ℃, the rotation speed is 140-160 rpm, and the shaking culture is performed.

8. The method as claimed in claim 1, wherein the amount of microbial suspension added in step 2) is 10% of the volume of the sludge in the aerobic tank.

9. The method for removing DEHP in landfill leachate according to claim 1, wherein the mass ratio of bacillus, pseudomonas and mycobacterium in the microbial suspension of step 2) is 2:1: 1.